\begin{figure}[H]
\centering
\begin{subfigure}[b]{.4\textwidth}
\centering
\figscale{
\begin{tikzpicture}[%
    >=stealth,
    shorten >=1pt,
    node distance=2cm,
    on grid,
    auto,
    state/.append style={minimum size=2em},
    thick,
    scale=0.4
  ]
    \node[state, rectangle, align=center] (N1) {$A{+}D$\\$\textcolor{BrickRed}{AG(\textcolor{Blue}{\$D})}$};
    \node[state] (N2) at (-4, -4) {$B{+}D$};
    \node[state] (N3) at (4, -4) {$C{+}D$};
\node[state] (N4) at (0, -8) {$D{+}E$};

    \path[->, BrickRed]
              (N1) edge [loop right] node {$\textcolor{Blue}{\$D}$} (N1)
              (N1) edge node [above right, pos=0.75] {$\textcolor{BrickRed}{AG(\textcolor{Blue}{\$D})}$} (N3)
              (N1) edge node [above left, pos=0.75] {$\textcolor{BrickRed}{AG(\textcolor{Blue}{\$D})}$} (N2)
(N2) edge [loop left] node {$\textcolor{Blue}{\$D}$} (N2)
(N3) edge [loop right] node {$\textcolor{Blue}{\$D}$} (N3)
(N3) edge node [below right] {$\textcolor{Blue}{\$D}$} (N4)
(N2) edge node [below left] {$\textcolor{Blue}{\$D}$} (N4);
  \end{tikzpicture}
}
\caption{Affichage \texttt{.dot}}
\end{subfigure}
\begin{subfigure}[b]{.4\textwidth}
\centering
\begin{minipage}{0.5\linewidth}
\begin{verbatim}
AG($D) = { 0 } {
  $D = { 0 }
  AG($D) = { 1 } {
    $D = { 1 }
    $D = { 2 }
  }
  AG($D) = { 3 } {
    $D = { 3 }
    $D = { 2 }
  }
}
\end{verbatim}
\end{minipage}
\caption{Affichage textuel}
\end{subfigure}
\caption{Preuve de $AG(\$D)$ pour l'état 0}
\label{fig:PreuveCheminAG}
\end{figure}